Method for producing shapes having circular corrugations

ABSTRACT

Shapes with circular corrugations are produced by spinning a sheet metal blank under the action of oppositely directed deforming and backing forces. The blank is given the configuration of an envelope of revolution with a continuously diverging flare and is secured at the end nearest to the geometrical apex of the flare, and the circular corrugations are formed sequentially from the smaller towards the larger diameter by applying a concentrated deforming force to the inside surface of the blank, the deforming force being directed along the blank axis.

TECHNICAL FIELD

The present invention relates to metalforming technique and isspecifically concerned with methods for producing shapes having circularcorrugations from sheet metal blanks by the spinning process.

BACKGROUND ART

Corrugated disk-typed shapes are presently produced from sheet metalmainly by stamping. With this technique, however, a blank is subjectedto deformation over the entire surface simultaneously, which requiresconsiderable forces. In addition, producing shapes having deepcorrugtions involves the use of a set of dies with progressivelyincreasing depth of impressions and necessitates annealing betweenoperations. This entails a high power consumption with a rather lowproductive capacity.

There is also known a method for producing shapes having circularcorrugations, wherein the corrugations are spinned by acting upon asheet metal blank with oppositely directed deforming and backing forces(USSR Inventor's Certificate No. 441,068, issued Aug. 30, 1974 Int. Cl.B21 D 13/10). In this method, disks having sawtooth-section corrugationsare produced from blanks in the form of the development of a cone. Sucha blank is deformed at the points of apices of all the corrugations overone of radial sections of the blank; the process proceeds byprogressively extending the zone of deformation and passing from oneradial section to another. A corrugated disk thus produced has anunclosed surface, which will necessitate an additional operation ofjoining and fastening together edges of a complex contour and henceinvolve additional labour and power consumption. Moreover, accomplishingthis method calls for an apparatus with shaping members (spinning tools)capable of varying the distance with respect to one another; thisentails a constructional complexity of the apparatus and tooling topractice the method.

The invention is based on the problem to provide a method for producingshapes having circular corrugations from sheet metal, which method makesit possible to produce such shapes with a broad range of dimensions andsubstantially any depth of the circular corrugations through changingthe configuration of a blank by acting thereupon with a concentrateddeforming force and offers at the same time low labour and powerconsumption.

DISCLOSURE OF INVENTION

The problem is solved by the provision of a method for producing shapeshaving circular corrugations through forming the corrugations by thespinning process which involves acting upon a sheet metal blank withoppositely directed deforming and backing forces, in which method theblank is given the configuration of an envelope of revolution with acontinuously diverging flare and is secured at the end nearest to thegeometrical apex of the flare, and the circular corrugations are formedsequentially from the smaller towards the larger diameter of the blankby applying a concentrated deforming force to the inside surface of theblank, the deforming forces being applied along the axis of the blank.

Such a method for producing shapes having circular corrugations offers alow power consumption, inasmuch as a blank in the form of a flarereadily lends itself to bending (turning out) at the points ofapplication of the deforming and backing forces, i.e. at the areas offorming the circular corrugations. The same fact accounts for thesimplicity of the method and possibility of forming corrugations withessentially any depth.

The small deforming forces in turn lower the requirements placed uponthe construction of the tooling needed to accomplish the method andreduce the metal content of the latter.

Owing to the fact that the process involves predominantly a bendingdeformation, the surface quality of formed circular corrugations isclose to that of the blank.

Finally, one of the prime attractions of the proposed method lies inthat the corrugated disks produced, when acted upon by external forces(such as pressure), can take a configuration close to that of the blank,which is essential for displacing diaphragms of fuel systems.

It is advisable that a blank be pre-extended by the deforming force atthe circular area of a corrugation to be formed till producing acircular shoulder. This will facilitate forming the corrugations whenthe blank is of a higher stiffness.

It is feasible that the point of application of the deforming force bemoved along a line corresponding to the contour of that wall of eachcorrugation which is disposed nearer to the blank axis. This will allowto increase the depth of the circular corrugations as well as to producedisks having circular corrugations from blanks with a spherical,parabolic, and like surface.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be explained by way of a detailed description ofthe method for producing shapes having circular corrugations andexamples of practicing thereof with reference to the accompanyingdrawings in which like parts are identified by like reference numeralsand in which:

FIG. 1 diagrammatically illustrates a blank for producing a shape andthe tooling to accomplish the method;

FIG. 2 diagrammatically illustrates the process of sequentially formingcircular corrugations;

FIG. 3 is a cross-sectional view of a shape having annular corrugationsproduced from a blank in the form of a truncated cone;

FIG. 4 diagrammatically illustrates the process of forming a circularshoulder on a higher-stiffness blank;

FIGS. 5a, b, c diagrammatically illustrates the sequence of the processof producing a shape having circular corrugations when feeding aspinning tool at an angle to the blank axis; and

FIG. 6 diagrammatically illustrates the process of producing a shapehaving circular corrugations from a hemispherical blank shown in adashed line.

BEST MODE FOR CARRYING OUT THE INVENTION

A blank 1 (FIG. 1) in the form of a closed envelope of revolution with acontinuously diverging flare is installed by its end nearest to thegeometrical apex of the flare on a die 2, centered, and secured by ahold-down 3. The die 2 has concentric ribs 4 spaced from one another ata distance equal to the spacing of the corrugations.

To effect the deforming force, the tooling of the method comprises aspinning tool 5 whose thickness and width depend on the dimensions ofthe corrugation to be formed. The working surface (end) of the spinningtool 5, contacting the surface of the blank 1, is rounded off and madeof a material which promotes sliding (such as of brass). For the samepurpose, grease is applied to the inside surface of the blank 1.

The die 2 with the blank 1 secured thereto is set in rotation. Thespinning tool 5 is brought within the blank and positioned radially sothat its end is substantially at the centre of a groove defined by thefirst and second (counting from the mandrel centreline) ribs.

The spinning tool 5 is moved along the axis of the blank 1 (as indicatedby the arrow A) until it contacts the inside surface of the latter.

A further longitudinal motion of the spinning tool 5 gives rise to aconcentrated deforming force acting from the side of the tool 5 and to abacking force acting from the side of that rib 4 of the die 2 which isdisposed nearer to the axis of the blank 1. Bending and rolling over theend of the spinning tool 5, the sheet metal of the blank turns out intoa mirror position to form a corrugation wall disposed nearer to theblank axis. The other wall of the corrugation is formed by theundeformed side of the blank 1, displaced to a new position up to thecontact with the other rib 4 of the groove of the die 2. After thecorrugation of a predetermined depth has been formed, the spinning tool5 is withdrawn to the initial position and traversed radially from thecentre towards the periphery of the blank for a distance equal to thespacing of the corrugations, and the second (counting from thecentreline of the shape) corrugation (FIG. 2) is formed. The process iscontinued until a shape (FIG. 3) with the desired amount of corrugationshas been produced.

The spinning tool may take the form of a roller (not shown) with aflange whose height somewhat exceeds the depth of the corrugation to beformed.

According to a modification of the invention, the blank 1 is preextendedby the deforming force at the circular (FIG. 4) area of a corrugation tobe formed till producing a circular shoulder 6 (FIG. 4). This operationis performed by a spinning tool in the form of a roller 7 whose axis issubstantially parallel with the axis of rotation of the blank 1. Theroller 7 is fed along the axis of the blank 1 into contact with theinside surface of the latter and until the circular shoulder 6 isformed, after which the roller 7 is withdrawn out of the blank 1 andreplaced by a spinning tool such as the plate 5 or a roller (not shown)whose rotational axis is disposed transversely with respect to the blankaxis, and forming a corrugation in the above-described manner isstarted. To form the next corrugation, the cycle is repeated.

According to another modification of the invention, the point ofapplication of the deforming force, i.e. the end of the spinning tool 5,is moved along a line corresponding to the contour of that wall of eachcorrugation which is disposed nearer to the blank axis.

When producing a shape from a blank having the configuration of acone-shaped envelope (FIGS. 5a, b, c), the spinning tool 5 is fedstraightlinearly at an angle ρ equal to the inclination angle of thesurface of that wall of each corrugation which is disposed nearer to theaxis of the blank 1. At the initial moment of forming the corrugations,the spinning tool 5 should be positioned so (FIG. 5b) that its sidesurface is spaced from the outer side of a corresponding rib at 1.5 to2δ, where δ is the thickness of the sheet metal.

When producing a shape from a blank having the configuration of ahemisphere (FIG. 6), the spinning tool is fed so that its end, i.e. thepoint of application of the deforming force, follows a curved linecorresponding to the contour of that wall of each corrugation which isdisposed nearer to the axis of the blank 1.

This is attained firstly by that the spinning tool is caused to follow acurvilinear template (not shown) corresponding to the surface of acircular area of the sphere, and secondly the surface of the rib 4disposed nearer to the axis of the blank 1 is also given theconfiguration of the circular area of the sphere.

EXAMPLE 1

A diaphragm was produced from a blank having the configuration of atruncated cone with a larger diameter of 620 mm. The sheet metal of theblank was 0.15 mm thick low-carbon steel.

Conditions of the method:

blank rotation, 80 m/min:

axial feed of spinning tool, 0.2 mm/rev.

A disk with fifty 4 mm deep circular corrugations was produced. Thesurface finish of the corrugations was close to that of the blank. Thedisk with circular corrugations was produced for use as a displacingdiaphragm of a conical tank.

EXAMPLE 2

A diaphragm was produced from a blank having the configuration of atruncated cone with a larger diameter of 400 mm. The sheet metal of theblank was 0.1 mm thick commercially pure titanium.

Conditions of the method:

blank rotation, 60 m/min;

axial feed of spinning tool, 0.1 mm/rev.

A disk with twenty 5 mm deep corrugations was produced. The surfacefinish of the corrugations was close to that of the blank.

EXAMPLE 3

A diaphragm with a single corrugation was produced from a blank havingthe configuration of a truncated cone with a larger diameter of 200 mm.The sheet metal of the blank was 0.1 mm thick commercially puretitanium.

Conditions of the method:

blank rotation, 50 m/min;

feed of spinning tool at an angle of ρ=10°, 0.2 mm/rev.

A diaphragm with a single 50 mm deep corrugation was produced.

EXAMPLE 4

A disk with circular corrugations was produced from a blank having theconfiguration of a truncated cone with a larger diameter of 1,200 mm.The sheet metal of the blank was 1 mm thick chromium-nickel stainlesssteel.

Conditions of the method:

blank rotation, 35 m/min;

axial feed of spinning tool, 0.5 mm/rev.

A disk with twenty 40 mm deep corrugations was produced.

EXAMPLE 5

A disk with circular corrugations was produced from a hemisphericalblank with a base diameter of 500 mm. The sheet metal of the blank was0.3 mm thick chromium-nickel stainless steel.

Conditions of the method:

blank rotation, 30 m/min;

template-controlled feed, 0.2 mm/rev.

A disk with fifteen circular corrugations with a depth varying from 5 to20 mm was produced.

The disk with circular corrugations was produced for use as a diaphragmof a spherical tank of a displacing system.

INDUSTRIAL APPLICABILITY

The invention is particularly useful for producing ring-shapedcorrugated disks used, depending on their purpose, as membranes,diaphragms and other shapes capable of varying within a broad rangetheir dimensions along the rotational axis under the action of externalforces.

We claim:
 1. A method for producing shapes having circular corrugationsby means of a spinning process, said method comprising:(a) providing ablank in the form of a closed envelope of revolution having acontinuously diverging flare; (b) securing the blank against a diehaving a plurality of spaced concentric ribs defining spaced concentricgrooves therebetween of different diameters; (c) providing a firstspinning tool; (d) spinning the blank about its axis; (e) aligning thespinning tool with one of the grooves in the die; (f) moving thespinning tool relative to the blank toward the die to provide adeforming force to form a corrugation wall; (g) withdrawing the spinningtool from the corrugation wall; (h) moving the tool radially relative tothe spinning axis to align the tool with another groove in the die; (i)moving the spinning tool relative to the blank toward the die to providea deforming force to form a second corrugation wall; and (j) withdrawingthe tool from the other groove.
 2. The method of claim 1 including thesteps of:(a) providing a second spinning tool in the form of a roller inwhich the axis of the roller is parallel to the spinning axis of theblank; (b) forming a circular shoulder in the blank adjacent a groove inthe die prior to applying forces by means of the first spinning tool bymoving the second spinning tool axially of the blank; and (c) producinga corrugation profile by means of the first spinning tool.
 3. The methodof claim 1 including the step of moving the first spinning tool alongthe contour of the wall of a groove in the die to provide a formingforce locally along the perimeter of the corrugation being formed. 4.The method of claim 3 wherein the moving step is along a linecorresponding to the innermost wall of the groove of the die relative tothe axis of the blank and said method begins at the innermost groovenearest the spinning axis of the blank and gradually progresses radiallyoutwardly toward the periphery of the blank.
 5. The method of claim 1wherein the moving step is performed in an axial direction and a formingforce is applied at an angle to the spinning axis of the blank, theangle being equal to the inclination angle of the groove internal wallrelative to the spinning axis of the blank.
 6. The method of claim 1wherein the moving step is performed in an angular direction relative tothe axis of the blank and along inclined sidewalls of the grooves, thesidewalls being inclined relative to the spinning axis of the blank, andincludes moving the spinning tool along the contour of the groovesidewalls to provide a forming force.